I was wondering if anyone know off hand how a computer PSU would isolate different loads so that a problem/short on one load would not damage the other. For example, the motherboard is supplied with a +5V line. The accessories (hard drive, DVD, etc.) also have a +5V line. How would a surge (+12V for example) on one line be prevented from going onto the other.
If there's nothing in the PSU, Is it the motherboard's responsibility to guard itself from this surge?